Biology subjects

Mizumoto, N.

Publications and source records attributed to Mizumoto, N..

At least 19 recordsLinked to original sources

bioRxiv2026

Body-like coordination emerges in paired termite locomotion

Coordinated group movements are often described as moving "like a single organism," yet this analogy is typically a metaphor. Individuals, interacting with each other, lack the functional integration of the body parts of a single organism. It remains unresolved whether movement coordination can truly reproduce body-like organization. Here we show that during tightly coordinated movement, pairs of termites use the same exploration-stabilization division of labor observed within a single moving body. Using posture tracking, we demonstrate that leader- follower asymmetries in tandem running mirror anterior-posterior asymmetries in individual locomotion, with exploratory motion concentrated at the front and smoother, shorter trajectories at the rear. Our mathematical model reveals that such body-like coordination emerges from hierarchical interactions between leaders and followers, described by the temporal convolution of past locational cues rather than instantaneous responses. These results identify a control principle of hierarchical structured movement coordination, providing a novel way to design collective behavior.

animal behavior and cognition↗

bioRxiv2026

Colony phase structure favors permanent worker evolution in juvenile social systems

Permanent workers in social insects, who forgo reproduction to help others, are a defining feature of superorganisms and a major evolutionary transition. Most theories assume that helping in the natal nests is inherently mutually exclusive from dispersal to found a new colony. This assumption holds for many adult societies whose workers cannot molt and change castes (e.g., Hymenoptera), but not for juvenile societies whose workers may differentiate and disperse after a period of helping (e.g., termites). The evolutionary advantage of permanent workers remains unknown in such juvenile societies with developmental flexibility. Here we develop a demographic model in which individuals can disperse either before or after a period of helping, capturing reversible helpers and permanent workers in termites. We found that permanent workers are favored when colony growth is divided into distinct ergonomic and reproductive phases, even if their performance is the same as that of reversible helpers. Without this phase separation, there is no selective advantage for workers to lose dispersal for colony foundation. After the phase separation, on the other hand, permanent workers increase continuous demographic growth and evolve through kin selection. By mapping diverse termite social systems onto a continuous landscape of ontogeny, the model traces a pathway linking different social forms. These results generalize social evolution theory beyond adult-worker systems by providing a demographic mechanism that favors the loss of the reproductive option.

evolutionary biology↗

bioRxiv2025

Diversification of pre-mating behaviors through temporal reordering of components

Many biological processes, including mating behavior, are structured as ordered sequences in which each step enables the next. Diversity of such processes usually arises through the addition or loss of components rather than through changes in their order, since reordering can disrupt functional integration. Here we show that reordering of the steps associated with termite nuptial pairing can generate behavioral diversity. In most termites, dispersed adults shed their wings before initiating tandem pairing, as wings interfere with communication between females and males. However, we found that in the Australian termite, Microcerotermes nervosus, tandem running occurs prior to wing shedding, and the act of tandem running itself facilitates dealation. Video tracking revealed that wing removal improves movement coordination, and comparative analysis of sympatric species showed that M. nervosus exhibits much higher tandem stability than others. These results suggest that enhanced movement coordination of this species may have potentiated step reordering. Our findings demonstrate that even functionally conserved sequences can be reorganized and that overcoming such constraints can open novel pathways for behavioral diversification.

animal behavior and cognition↗

bioRxiv2025

Evolution of sideways locomotion in crabs

The evolutionary change in the mode of locomotion is often a major evolutionary event, triggering diversification. Sideways locomotion is a defining feature of true crabs (Brachyura) and may have contributed to their ecological success. Yet, the evolutionary origin of this unique behavior remains unknown. Here we show that the prevalence of sideways locomotion in true crabs reflects a single evolutionary origin from a forward-moving ancestor. Our behavioral analysis of 50 live crab species indicates that crab locomotion can be broadly separated into two predominant modes, sideways and forward locomotion. The phylogenetic comparative analysis revealed a single origin of sideways locomotion, with multiple independent reversions to forward locomotion in ecologically specialized groups. The species richness data show that the lineage in which sideways locomotion originated is far more diverse than its nearest outgroups. These results are consistent with the idea that sideways locomotion acted as a key innovation contributing to the evolutionary diversification of true crabs. Such a rare but innovative behavioral trait provides a framework for understanding how locomotor modes shape evolutionary diversification in animals.

evolutionary biology↗

bioRxiv2025

Observation of tandem running behavior in mating pairs of Asian dampwood termite, Hodotermopsis sjostedti

As a social insect, termite colonies can grow to a group of millions of individuals, yet all colonies start from a single mating pair. Recent studies indicate that the pair formation process shows a large diversity among species, especially in basal lineages. Thus, comparative information is integral to estimating the ancestral state of this essential stage of the termite life cycle. The Asian dampwood termite, Hodotermopsis sjostedti, has been well-studied as a model basal termite of caste differentiation processes. Yet, their pair formation remains undocumented. In this study, we found that mating pairs of H. sjostedti show clear tandem running behavior. Both females and males played a leading role, with females showing more leader roles, and they switched their leading roles even within the same pair. We also found that dish size affected tandem movement coordination; pairs showed faster and more stable tandem running in a larger dish. We provide a tracking dataset of 17 body parts, including antennal and leg movements during tandem runs, which can be utilized in future comparative studies. This study supports the idea that tandem running existed in the early ancestors of termites and sheds light on the origin of termite mate pairing.

animal behavior and cognition↗

bioRxiv2025

Maintaining tandem movement cohesion through antennal movements in termites

How do animals coordinate their motion during migration? Traditional models of collective motion, for example, describing bird flocks or fish schools, rely on visual interactions. However, many animals are blind, requiring movement coordination through maintenance of physical contact. The risks and cost of becoming accidentally separated may encourage the evolution of compensatory strategies. Here we study tandem running in blind termites. We quantitatively investigate how these animals use their appendages to maintain stable pair movements. During tandem runs, male followers use shorter palps and longer antennae to maintain physical contact with female leaders. Our posture-tracking analysis revealed that termites dynamically change their antennal movements. Males stabilize their antennae to maintain contact with their partners while their palps are in contact. When the male palps lost contact with a female, males started swinging antennae while increasing movement speed. Antennae removal experiments revealed that antennal swinging contributes to pair maintenance, and males compensate for single antenna loss by increasing the swinging of the remaining one. By providing detailed information on contact-based movement coordination, our results contribute to understanding the diversity of animal collective behavior.

animal behavior and cognition↗

bioRxiv2024

The strength of sexual signals predicts same-sex paring in termites

Same-sex sexual behavior (SSB) is an enigma in behavioral ecology as it does not result in reproduction. Proximately, the evolution of sexual signals is critical for the evolution of SSB in a sex-specific manner. For signal receivers, the loss of sexual signals leads to smaller phenotypic sex differences, leading to frequent accidental SSB between receivers. Alternatively, for senders, sexual signals could help locate another sender, enhancing intentional SSB as in heterosexual pairing. Here, we demonstrate this link between sex pheromone signaling and the frequency of same-sex pairing in two Coptotermes termites that use the same chemical as sex pheromones but in different quantities. In termites, mating pairs engage in tandem runs, where a male follows a female with sex pheromones. We found that female-female tandems were more stable in C. formosanus, whose females produce more pheromones, while the male-male interactions were more frequent in C. gestroi, whose females produce fewer pheromones. Thus, stronger pheromones lead to sender-sender SSB, while weaker pheromones lead to receiver-receiver SSB. In both species, same-sex tandems were less stable than heterosexual tandems, contrasting with Reticulitermes, another termite group that shows frequent same-sex tandems. The proximate mechanism of SSB is diverse, reflecting the heterosexual context.

animal behavior and cognition↗

bioRxiv2024

Wasted efforts impair random search efficiency and reduce choosiness in mate-pairing termites

Random search theories predict that animals employ movement patterns that optimize encounter rates with target resources. However, animals are not always able to achieve the best search strategy. Energy depletion, for example, limits searchers movement activities, forcing them to adjust their behaviors before and after encounters. Here, we quantified the cost of mate search in a termite, Reticulitermes speratus, and revealed that the searching cost reduces the selectivity of mating partners. After a dispersal flight, termites search for a mating partner with limited reserved energy. We found that their movement activity and diffusiveness progressively declined over extended mate search. Our data-based simulations qualitatively confirmed that the reduced movement diffusiveness decreased the searching efficiency. Also, prolonged search periods reduced colony foundation success and the number of offspring. Thus, mate search imposes doubled costs on termites. Finally, we found that termites with an extended mate search reduced the selectivity of mating partners, where males immediately paired with any encountering females. Thus, termites dramatically changed their mate search behavior depending on their physiological conditions. Our finding highlights that accounting for the searchers internal states is essential to fill the gap between random search theories and empirical behavioral observations.

ecology↗

bioRxiv2023

The significance of social interactions in synchronized swarming flight in a termite

In social insect colonies, individuals of working caste coordinate their actions to manage various collective tasks. Such collective behaviors are observed not only in working castes but also in reproductives. During certain seasons, newly emerged winged reproductives (alates) fly from the nest to disperse and find mating partners in a synchronized manner. Although this "swarming" behavior is one of the collective behaviors that involve the greatest number of individuals in social insects, underlying social interactions remain unexplored. Here, we show that synchronized flight among colony members results from collective decision-making. Our simple simulation model suggests that social interactions in a large group of alates enable synchronized flight within a nest under fluctuating environmental conditions. This model is supported by empirical experiments using a termite Reticulitermes kanmonensis. Under the semi-field environment with fluctuating temperatures, alates within the same colony synchronized their dispersal flight under higher air temperatures, while dispersal flight was suppressed under lower temperatures. Furthermore, termites could synchronize their dispersal flights even under laboratory conditions with constant temperature, indicating that environmental cues are not always necessary for synchronization. In either case, higher synchronization happened with a larger number of alates. All these results demonstrate that both environmental and social factors interplay to enable the synchronized swarming flight of social insects.

animal behavior and cognition↗

bioRxiv2023

Extinct and extant termites reveal the fidelity of behavior fossilization in amber

Fossils encompassing multiple individuals provide rare direct evidence of behavioral interactions among extinct organisms. However, the fossilization process can alter the spatial relationship between individuals and hinder behavioral reconstruction. Here, we report a Baltic amber inclusion preserving a female-male pair of the extinct termite species Electrotermes affinis. The head-to-abdomen contact in the fossilized pair resembles the tandem courtship behavior of extant termites, although their parallel body alignment differs from the linear alignment typical of tandem runs. To solve this inconsistency, we simulated the first stage of amber formation, the immobilization of captured organisms, by exposing living termite tandems to sticky surfaces. We found that the posture of the fossilized pair matches trapped tandems and differs from untrapped tandems. Thus, the fossilized pair likely is a tandem running pair, representing the first direct evidence of the mating behavior of extinct termites. Furthermore, by comparing the positions of partners on a sticky surface and in the amber inclusion, we estimated to 67% the probability that the leader role in the fossilized tandem was performed by a male. Our results demonstrate that past behavioral interactions can be reconstructed despite the spatial distortion of body poses during fossilization. Our taphonomic approach clarifies how certain behaviors can be inferred from fossil occurrences.

evolutionary biology↗

bioRxiv2022

TManual: Assistant for manually measuring length development in structures built by animals

O_LIStructures built by animals are extended phenotypes, and animal behavior can be better understood by recording the temporal development of structure construction. For most subterranean and wood-boring animals, these structures consist of gallery systems, such as burrows made by mice, tunnel foraging by termites, and nest excavation in ants. Measurement of the length development of such structures is often performed manually. However, it is time-consuming and cognitively costly to track length development in nested branching structures, hindering the quantitative determination of temporal development. C_LIO_LIHere, I introduce TManual, which aids the manual measurement of structure length development using a number of images. TManual provides a user interface to draw gallery structures and take over all other processes handling input datasets (e.g., zero-adjustment, scaling the units, measuring the length, assigning gallery identities, and extracting network structures). Thus, users can focus on the measuring process without interruptions. C_LIO_LIAs examples, I provide the results of the analysis of a dataset of tunnel construction by three termite species after successfully processing 1,125 images in [~]3 h. The output datasets clearly visualized the interspecific variation in tunneling speed and branching structures. Furthermore, I applied TManual to a complex gallery system by another termite species and extracted network structures. C_LIO_LIMeasuring the lengths of objects from images is an essential task in biological observation. TManual helps users handle many images in a realistic time scale, enabling a comparative analysis across a wide array of species. TManual does not require programming skills and outputs a tidy data frame in CSV format. Therefore, it is suitable for any user who wants to perform image analysis for length measurements. C_LI

animal behavior and cognition↗

bioRxiv2022

Cryptic functional diversity in ant tandem runs

Ants have evolved diverse recruitment methods to guide colony members to valuable resources, such as food or nest sites. One of these methods, tandem running, consists of an informed leader directly guiding a naive follower every step of the way from nest to resource. Although this behavior appears superficially similar in the different ant taxa in which it has independently evolved, this similarity could conceal underlying functional and mechanistic differences. Here we present a combined network and information-theoretic analysis, which reveals fundamental differences in the tandem recruitment between two distantly related ant genera, Temnothorax and Diacamma. Temnothorax uses tandem running to recruit additional recruiters, whereas Diacamma uses it principally to move the passive majority of the colony, a task that Temnothorax accomplishes with a different behavior, social carrying. Accordingly, the structure of the tandem run recruitment networks of Diacamma was different from those of Temnothorax, with Diacamma networks more closely resembling the social carrying networks of Temnothorax. Furthermore, an information-theoretic analysis of the spatial trajectories of leaders and followers revealed that Diacamma tandem runs lack bidirectional information flow, the signature of route-learning in Temnothorax tandem runs. These results suggest that Diacamma uses tandem runs not to share information, but to transport nestmates. By quantifying the cryptic diversity of communication behavior, this study increases the resolution of our understanding of animal societies.

animal behavior and cognition↗

bioRxiv2022

Ancestral sex-role plasticity facilitates the evolution of same-sex sexual behaviour

Recent attempts to explain the evolutionary prevalence of same-sex sexual behaviour (SSB) have focused on the role of indiscriminate mating. However, in many cases, SSB involves plastically adjusting sex roles to achieve successful courtship or pairing. To evaluate this overlooked factor, we tested whether ancestral sex-role plasticity facilitated the evolution of SSB in the termite Reticulitermes speratus. Male termites follow females in paired tandems before mating, and movement patterns are sexually dimorphic. Adaptive same-sex tandems occur in both sexes. We show that in such cases, one partner adopts the other sexs movement patterns, resulting in behavioural dimorphism. Data-based simulations confirmed that this socially-cued plasticity contributes to pair maintenance because dimorphic movements improve reunion success upon accidental separation. Phylogenetic analysis indicated that the ancestors of modern termites lack consistent sex roles during pairing, indicating that R. speratus inherited the plasticity from the ancestor. Socio-environmental induction of ancestral behavioural potential may be of widespread importance to the evolutionary maintenance of SSB.

animal behavior and cognition↗

bioRxiv2021

The history of body size evolution in termites

Termites are social cockroaches. Because non-termite cockroaches are larger than basal termite lineages, which themselves include large termite species, it has been proposed that termites experienced a unidirectional body size reduction since they evolved eusociality. However, the validity of this hypothesis remains untested in a phylogenetic framework. Here, we reconstructed termite body size evolution using head width measurements of 1638 modern and fossil termite species. We found that the unidirectional body size reduction model was only supported by analyses excluding fossil species. Analyses including fossil species suggested that body size diversified along with speciation events and estimated that the size of the common ancestor of modern termites was comparable to that of modern species. Our analyses further revealed that body size variability among species, but not body size reduction, is associated with features attributed to advanced termite societies. Our results suggest that miniaturization took place at the origin of termites, while subsequent complexification of termite societies did not lead to further body size reduction.

evolutionary biology↗

bioRxiv2021

Transoceanic voyages of drywood termites (Isoptera: Kalotermitidae) inferred from extant and extinct species

Termites are major decomposers of organic matter in terrestrial ecosystems and the second most diverse lineage of social insects. The Kalotermitidae, the second-largest termite family, are widely distributed across tropical and subtropical ecosystems, where they typically live in small colonies confined to single wood items inhabited by individuals with no foraging abilities. How the Kalotermitidae have acquired their global distribution patterns remains unresolved. Similarly, it is unclear whether foraging is ancestral to Kalotermitidae or was secondarily acquired in a few species. These questions can be addressed in a phylogenetic framework. We inferred time-calibrated phylogenetic trees of Kalotermitidae using mitochondrial genomes and nuclear ribosomal RNA genes of [~]120 species, about 27% of kalotermitid diversity, including representatives of 22 of the 23 kalotermitid genera. We found that extant kalotermitids shared a common ancestor 81 Mya (72-91 Mya 95% HPD), indicating that a few disjunctions among early-diverging kalotermitid lineages may predate Gondwana breakup. However, most of the [~]40 disjunctions among biogeographic realms were dated at less than 50 Mya, indicating that transoceanic dispersals, and more recently human-mediated dispersals, have been the major drivers of the global distribution of Kalotermitidae. Our phylogeny also revealed that the capacity to forage is often found in early-diverging kalotermitid lineages, implying that the ancestors of Kalotermitidae were able to forage among multiple wood pieces. Our phylogenetic estimates provide a platform for a critical taxonomic revision of the family and for future comparative analyses of Kalotermitidae.

evolutionary biology↗

bioRxiv2021

Coordination of movement via complementary interactions of leaders and followers in termite mating pairs

Leadership of animal group movements depends on social feedback, hence leaders signals and followers responses should be attuned to each other. However, leader and follower roles are difficult to disentangle in species with high levels of coordination. To overcome this challenge, we investigated a simple case of movement coordination: termite pairs in which a female leads a male as they search for a nest site. To tease apart leader and follower roles, we created conspecific and heterospecific pairs of Coptotermes gestroi and C. formosanus, which share a pairing pheromone so that males follow females of either species. Conspecific pairs were stable for both species, even though C. gestroi females produce less pheromone than C. formosanus. Heterospecific pairs with C. gestroi males were also stable, but not those with C. formosanus males. We attributed this difference to the C. gestroi males unique capacity to follow females that release small amounts of pheromone; C. formosanus males cannot follow or reject C. gestroi females as unsuitable. This conclusion was supported by an information-theoretic analysis that detected information flow from C. formosanus females to C. gestroi males as in conspecific pairs, but not from C. gestroi females to C. formosanus males. Despite their following ability, C. gestroi males lost to C. formosanus males in competitions to follow C. formosanus females. Thus, partner selection has shaped the species-specific association of mating pairs. Our results demonstrate that a similar level of coordination can emerge from distinct sets of complementary sender-receiver interactions.

animal behavior and cognition↗

bioRxiv2019

Parameter tuning facilitates the evolution of diverse tunneling patterns in termites

The nest structures built by social insects are complex group-level patterns that emerge from interactions among individuals following simple behavioral rules. The theory of complex systems predicts that there is no simple one-to-one relationship between variations in collective patterns and variation in individual behaviors; therefore, it is essential to know how actual behavior evolves to change pattern formation. Here we demonstrate that the evolutionary divergence of termite tunneling patterns is achieved by quantitative tuning of shared behavioral rules, rather than the acquisition of novel behaviors. We compared tunnel formation between two closely related species, Reticulitermes tibialis and Heterotermes aureus, and found that H. aureus builds more highly branched tunnels than R. tibialis. Our behavioral analysis and data-based modeling revealed that these species share the same behavioral repertoire, but a quantitative difference in the probability of sidewall excavation leads to diverse tunneling patterns. In contrast, we also found that Paraneotermes simplicicornis, which evolved tunneling independently, possesses a distinct behavioral repertoire, but shows convergence of branching patterns with R. tibialis. These results elucidate the complex relationship between individual behavior and group-level patterns; in some cases, distinct behavioral rules can produce similar group-level patterns, but in others, a common rule set can yield distinct patterns via parameter tuning. The evolutionary process of collective behavior is flexible and much more complex than we can infer from group-level patterns alone.

animal behavior and cognition↗

bioRxiv2019

Ants acknowledge information to control its rate of transfer

Behavioral correlations stretching over time are an essential but often neglected aspect of interactions among animals. These correlations pose a challenge to current behavioral-analysis methods that lack effective means to analyze complex series of interactions. Here we show that non-invasive information-theoretic tools can be used to reveal communication protocols that guide complex social interactions by measuring simultaneous flows of different types of information between subjects. We demonstrate this approach by showing that the tandem-running behavior of the ant Temnothorax rugatulus and that of the termites Coptotermes formosanus and Reticulitermes speratus are governed by different communication protocols. Our discovery reconciles the diverse ultimate causes of tandem running across these two taxa with their apparently similar signaling mechanisms. We show that bidirectional flow of information is present only in ants and is consistent with the use of acknowledgement signals to regulate the flow of directional information.

animal behavior and cognition↗